Reactive liquid polymers are polymers having a hydrocarbon backbone and including reactive groups generally on both terminal positions. Among reactive or functional groups available in the terminal positions of such reactive liquid polymers are carboxyl groups. In certain reactive liquid polymers, reactive or functional groups such as carboxyl groups may be pendant from the backbone in addition to being present as terminal reactive groups. Such pendant groups are not necessarily identical to the terminal groups in functionality.
Reactive liquid polymers typically are 100% solids and yet, while containing no solvents, demonstrate generally liquid behavior and are possessed of a specific gravity generally less than 1.00. Reactive liquid polymers find uses relating to the reactive or functional groups in the terminal positions of the reactive liquid polymer which provide reaction sites enabling the reactive liquid polymers to react with other materials such as in a curing process. Such reactions can involve chain extension and cross linking, thereby forming solid elastomeric products.
From time to time it is desirable that elastomeric products produced employing reactive liquid polymers be possessed of hydrophilic properties. Where, for example, a reactive liquid polymer is polymerized and employed in conjunction with other elastomeric materials in forming an elastomeric object, inclusion of hydrophilic properties in the resulting elastomeric object may be desirable.
Owing to a terminal group that may provide reactive or functional capabilities, these reactive liquid polymers tend to provide a mechanism for introducing rubbery characteristics into compounds not otherwise demonstrating elastomeric properties. So, for example, carboxyl terminated reactive liquid polymers find utility in blends with unsaturated polyester resins that would otherwise be inherently brittle. Incorporation of carboxyl terminated reactive liquid polymers into elastomeric systems employed for the forming of elastomeric objects and coatings can enhance the elongation properties of the resulting objects and coatings in addition to providing improved impact resistance.
Reactive liquid polymers containing terminal carboxyl groups typically can be cured employing agents tending to react with the carboxyl groups of two or more molecules of the reactive liquid polymer. Such agents might include: (1) epoxy resins; (2) aziridinyl-type compounds; (3) carbodiimides; and (4) condensation resin intercures. It is also possible to obtain a cure employing polyamines such as triethylene tetraamine and with polyvalent metallic compounds such as zinc oxide. Such cures often tend to be thermoplastic and therefore weak. Where the backbone of a carboxyl terminated reactive liquid polymer is unsaturated, curing may be accomplished employing sulfur, but the resulting products tend to be relatively weak and somewhat brittle. It has been found that epoxy curing generally provides a cured reactive liquid polymer product having broadly satisfactory properties. For example, in one application, carboxyl terminated reactive liquid polymers are applied and cured employing an epoxy in place to provide a so-called moisture barrier in electrical systems whereby the cured reactive liquid polymer blocks access of moisture to electrical connections.
Phosphazene is a well known compound comprising phosphorous and nitrogen. Phosphazene is generally regarded as being a ring or chain polymer typically including two substituents on each phosphorus atom. Most typically, the phosphazene is characterized by cyclic trimer, cyclic tetramer, and high polymeric structures. It has been suggested that phosphazene be employed for crosslinking hydroxyl terminated liquid polybutadiene compounds and that phosphazene be employed to provide substitution products in reactions with amines, alcohols and phenols, and to activate carboxylic acid.
Reaction product derivatives of carboxyl terminated reactive liquid polymers having hydrophilic properties upon curing could find application scavenging water within sealed cavities while providing desirable rubbery or elastomeric properties. Such a hydrophilic polymer could find application in polymeric systems where the inclusion of a water scavenger may be desirable.